It is not too surprising that Ubuntu came in first in DesktopLinux.com's 2007 Desktop Linux Market Survey, or that Firefox was the topmost browser by far. More interesting is that for the first time ever in the site's annual surveys, GNOME surpassed KDE among desktop environments (45% over 35%), with Xfce a solid third (8%).

From what I've seen, it seems KDE vs Gnome in terms of speed depends a bit on what you think is important. KDE apps draw faster (Qt is more efficient than GTK), but Gnome apps start faster due to GCC and the other parts of the stack below the DE being better with C than C++. Wen run from within KDE, KDE apps start almost as fast as Gnome ones, but run from Gnome, KDE apps start very slow. Time will fix this, as things like the dynamic linker get better at C++ code.